libs/ardour/session_process.cc

   1 /*
   2     Copyright (C) 1999-2002 Paul Davis
   3
   4     This program is free software; you can redistribute it and/or modify
   5     it under the terms of the GNU General Public License as published by
   6     the Free Software Foundation; either version 2 of the License, or
   7     (at your option) any later version.
   8
   9     This program is distributed in the hope that it will be useful,
  10     but WITHOUT ANY WARRANTY; without even the implied warranty of
  11     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12     GNU General Public License for more details.
  13
  14     You should have received a copy of the GNU General Public License
  15     along with this program; if not, write to the Free Software
  16     Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  17
  18     $Id$
  19 */
  20
  21 #include <cmath>
  22 #include <cerrno>
  23 #include <algorithm>
  24 #include <unistd.h>
  25
  26 #include <pbd/error.h>
  27
  28 #include <glibmm/thread.h>
  29
  30 #include <ardour/ardour.h>
  31 #include <ardour/session.h>
  32 #include <ardour/timestamps.h>
  33 #include <ardour/audio_diskstream.h>
  34 #include <ardour/audioengine.h>
  35 #include <ardour/slave.h>
  36 #include <ardour/auditioner.h>
  37 #include <ardour/cycles.h>
  38 #include <ardour/cycle_timer.h>
  39
  40 #include "i18n.h"
  41
  42 using namespace ARDOUR;
  43 using namespace PBD;
  44 using namespace std;
  45
  46 void
  47 Session::process (jack_nframes_t nframes)
  48 {
  49         if (synced_to_jack() && waiting_to_start) {
  50                 if ( _engine.transport_state() == AudioEngine::TransportRolling) {
  51                         actually_start_transport ();
  52                 }
  53         }
  54
  55         if (non_realtime_work_pending()) {
  56                 if (g_atomic_int_get (&butler_should_do_transport_work) == 0) {
  57                         post_transport ();
  58                 }
  59         }
  60
  61         (this->*process_function) (nframes);
  62
  63         SendFeedback (); /* EMIT SIGNAL */
  64 }
  65
  66 void
  67 Session::prepare_diskstreams ()
  68 {
  69         boost::shared_ptr<DiskstreamList> dsl = diskstreams.reader();
  70         for (DiskstreamList::iterator i = dsl->begin(); i != dsl->end(); ++i) {
  71                 (*i)->prepare ();
  72         }
  73 }
  74
  75 int
  76 Session::no_roll (jack_nframes_t nframes, jack_nframes_t offset)
  77 {
  78         jack_nframes_t end_frame = _transport_frame + nframes;
  79         int ret = 0;
  80         bool declick = get_transport_declick_required();
  81         boost::shared_ptr<RouteList> r = routes.reader ();
  82
  83         if (_click_io) {
  84                 _click_io->silence (nframes, offset);
  85         }
  86
  87         if (g_atomic_int_get (&processing_prohibited)) {
  88                 for (RouteList::iterator i = r->begin(); i != r->end(); ++i) {
  89                         (*i)->silence (nframes, offset);
  90                 }
  91                 return 0;
  92         }
  93
  94         for (RouteList::iterator i = r->begin(); i != r->end(); ++i) {
  95
  96                 if ((*i)->hidden()) {
  97                         continue;
  98                 }
  99
 100                 (*i)->set_pending_declick (declick);
 101
 102                 if ((*i)->no_roll (nframes, _transport_frame, end_frame, offset, non_realtime_work_pending(),
 103                                    actively_recording(), declick)) {
 104                         error << string_compose(_("Session: error in no roll for %1"), (*i)->name()) << endmsg;
 105                         ret = -1;
 106                         break;
 107                 }
 108         }
 109
 110         return ret;
 111 }
 112
 113 int
 114 Session::process_routes (jack_nframes_t nframes, jack_nframes_t offset)
 115 {
 116         bool record_active;
 117         int  declick = get_transport_declick_required();
 118         bool rec_monitors = get_rec_monitors_input();
 119         boost::shared_ptr<RouteList> r = routes.reader ();
 120
 121         if (transport_sub_state & StopPendingCapture) {
 122                 /* force a declick out */
 123                 declick = -1;
 124         }
 125
 126         record_active = actively_recording(); // || (get_record_enabled() && get_punch_in());
 127
 128         for (RouteList::iterator i = r->begin(); i != r->end(); ++i) {
 129
 130                 int ret;
 131
 132                 if ((*i)->hidden()) {
 133                         continue;
 134                 }
 135
 136                 (*i)->set_pending_declick (declick);
 137
 138                 if ((ret = (*i)->roll (nframes, _transport_frame, _transport_frame + nframes, offset, declick, record_active, rec_monitors)) < 0) {
 139
 140                         /* we have to do this here. Route::roll() for an AudioTrack will have called AudioDiskstream::process(),
 141                            and the DS will expect AudioDiskstream::commit() to be called. but we're aborting from that
 142                            call path, so make sure we release any outstanding locks here before we return failure.
 143                         */
 144
 145                         boost::shared_ptr<DiskstreamList> dsl = diskstreams.reader();
 146                         for (DiskstreamList::iterator ids = dsl->begin(); ids != dsl->end(); ++ids) {
 147                                 (*ids)->recover ();
 148                         }
 149
 150                         stop_transport ();
 151                         return -1;
 152                 }
 153         }
 154
 155         return 0;
 156 }
 157
 158 int
 159 Session::silent_process_routes (jack_nframes_t nframes, jack_nframes_t offset)
 160 {
 161         bool record_active = actively_recording();
 162         int  declick = get_transport_declick_required();
 163         bool rec_monitors = get_rec_monitors_input();
 164         boost::shared_ptr<RouteList> r = routes.reader ();
 165
 166         if (transport_sub_state & StopPendingCapture) {
 167                 /* force a declick out */
 168                 declick = -1;
 169         }
 170
 171         for (RouteList::iterator i = r->begin(); i != r->end(); ++i) {
 172
 173                 int ret;
 174
 175                 if ((*i)->hidden()) {
 176                         continue;
 177                 }
 178
 179                 if ((ret = (*i)->silent_roll (nframes, _transport_frame, _transport_frame + nframes, offset, record_active, rec_monitors)) < 0) {
 180
 181                         /* we have to do this here. Route::roll() for an AudioTrack will have called AudioDiskstream::process(),
 182                            and the DS will expect AudioDiskstream::commit() to be called. but we're aborting from that
 183                            call path, so make sure we release any outstanding locks here before we return failure.
 184                         */
 185
 186                         boost::shared_ptr<DiskstreamList> dsl = diskstreams.reader();
 187                         for (DiskstreamList::iterator ids = dsl->begin(); ids != dsl->end(); ++ids) {
 188                                 (*ids)->recover ();
 189                         }
 190
 191                         stop_transport ();
 192                         return -1;
 193                 }
 194         }
 195
 196         return 0;
 197 }
 198
 199 void
 200 Session::commit_diskstreams (jack_nframes_t nframes, bool &needs_butler)
 201 {
 202         int dret;
 203         float pworst = 1.0f;
 204         float cworst = 1.0f;
 205
 206         boost::shared_ptr<DiskstreamList> dsl = diskstreams.reader();
 207         for (DiskstreamList::iterator i = dsl->begin(); i != dsl->end(); ++i) {
 208
 209                 if ((*i)->hidden()) {
 210                         continue;
 211                 }
 212
 213                 /* force all diskstreams not handled by a Route to call do their stuff.
 214                  */
 215
 216                 if ((dret = (*i)->process (_transport_frame, nframes, 0, actively_recording(), get_rec_monitors_input())) == 0) {
 217                         if ((*i)->commit (nframes)) {
 218                                 needs_butler = true;
 219                         }
 220
 221                 } else if (dret < 0) {
 222                         (*i)->recover();
 223                 }
 224
 225                 pworst = min (pworst, (*i)->playback_buffer_load());
 226                 cworst = min (cworst, (*i)->capture_buffer_load());
 227         }
 228
 229         uint32_t pmin = g_atomic_int_get (&_playback_load);
 230         uint32_t pminold = g_atomic_int_get (&_playback_load_min);
 231         uint32_t cmin = g_atomic_int_get (&_capture_load);
 232         uint32_t cminold = g_atomic_int_get (&_capture_load_min);
 233
 234         g_atomic_int_set (&_playback_load, (uint32_t) floor (pworst * 100.0f));
 235         g_atomic_int_set (&_capture_load, (uint32_t) floor (cworst * 100.0f));
 236         g_atomic_int_set (&_playback_load_min, min (pmin, pminold));
 237         g_atomic_int_set (&_capture_load_min, min (cmin, cminold));
 238
 239         if (actively_recording()) {
 240                 set_dirty();
 241         }
 242 }
 243
 244 void
 245 Session::process_with_events (jack_nframes_t nframes)
 246 {
 247         Event* ev;
 248         jack_nframes_t this_nframes;
 249         jack_nframes_t end_frame;
 250         jack_nframes_t offset;
 251         bool session_needs_butler = false;
 252         jack_nframes_t stop_limit;
 253         long           frames_moved;
 254
 255         /* make sure the auditioner is silent */
 256
 257         if (auditioner) {
 258                 auditioner->silence (nframes, 0);
 259         }
 260
 261         /* handle any pending events */
 262
 263         while (pending_events.read (&ev, 1) == 1) {
 264                 merge_event (ev);
 265         }
 266
 267         /* if we are not in the middle of a state change,
 268            and there are immediate events queued up,
 269            process them.
 270         */
 271
 272         while (!non_realtime_work_pending() && !immediate_events.empty()) {
 273                 Event *ev = immediate_events.front ();
 274                 immediate_events.pop_front ();
 275                 process_event (ev);
 276         }
 277
 278         if (!process_can_proceed()) {
 279                 no_roll (nframes, 0);
 280                 return;
 281         }
 282
 283         if (events.empty() || next_event == events.end()) {
 284                 process_without_events (nframes);
 285                 return;
 286         }
 287
 288         end_frame = _transport_frame + nframes;
 289
 290         {
 291                 Event* this_event;
 292                 Events::iterator the_next_one;
 293
 294                 if (post_transport_work & (PostTransportLocate|PostTransportStop)) {
 295                         no_roll (nframes, 0);
 296                         return;
 297                 }
 298
 299                 if (!_exporting && _slave) {
 300                         if (!follow_slave (nframes, 0)) {
 301                                 return;
 302                         }
 303                 }
 304
 305                 if (_transport_speed == 0) {
 306                         no_roll (nframes, 0);
 307                         return;
 308                 }
 309
 310                 if (actively_recording()) {
 311                         stop_limit = max_frames;
 312                 } else {
 313
 314                         if (Config->get_stop_at_session_end()) {
 315                                 stop_limit = current_end_frame();
 316                         } else {
 317                                 stop_limit = max_frames;
 318                         }
 319                 }
 320
 321                 if (maybe_stop (stop_limit)) {
 322                         no_roll (nframes, 0);
 323                         return;
 324                 }
 325
 326                 this_event = *next_event;
 327                 the_next_one = next_event;
 328                 ++the_next_one;
 329
 330                 offset = 0;
 331
 332                 while (nframes) {
 333
 334                         if (this_event == 0 || this_event->action_frame > end_frame || this_event->action_frame < _transport_frame) {
 335
 336                                 this_nframes = nframes;
 337
 338                         } else {
 339
 340                                 /* compute nframes to next event */
 341
 342                                 if (this_event->action_frame < end_frame) {
 343                                         this_nframes = nframes - (end_frame - this_event->action_frame);
 344                                 } else {
 345                                         this_nframes = nframes;
 346                                 }
 347                         }
 348
 349                         if (this_nframes) {
 350
 351                                 click (_transport_frame, nframes, offset);
 352
 353                                 /* now process frames between now and the first event in this block */
 354                                 prepare_diskstreams ();
 355
 356                                 if (process_routes (this_nframes, offset)) {
 357                                         no_roll (nframes, 0);
 358                                         return;
 359                                 }
 360
 361                                 commit_diskstreams (this_nframes, session_needs_butler);
 362
 363                                 nframes -= this_nframes;
 364                                 offset += this_nframes;
 365
 366                                 frames_moved = (jack_nframes_t) floor (_transport_speed * this_nframes);
 367
 368                                 if (frames_moved < 0) {
 369                                         decrement_transport_position (-frames_moved);
 370                                 } else {
 371                                         increment_transport_position (frames_moved);
 372                                 }
 373
 374                                 maybe_stop (stop_limit);
 375                                 check_declick_out ();
 376                         }
 377
 378                         /* now handle this event and all others scheduled for the same time */
 379
 380                         while (this_event && this_event->action_frame == _transport_frame) {
 381                                 process_event (this_event);
 382
 383                                 if (the_next_one == events.end()) {
 384                                         this_event = 0;
 385                                 } else {
 386                                         this_event = *the_next_one;
 387                                         ++the_next_one;
 388                                 }
 389                         }
 390
 391                         /* if an event left our state changing, do the right thing */
 392
 393                         if (non_realtime_work_pending()) {
 394                                 no_roll (nframes, offset);
 395                                 break;
 396                         }
 397
 398                         /* this is necessary to handle the case of seamless looping */
 399                         /* not sure if it will work in conjuction with varispeed */
 400                         end_frame = _transport_frame + nframes;
 401
 402                 }
 403
 404                 set_next_event ();
 405
 406         } /* implicit release of route lock */
 407
 408
 409         if (session_needs_butler) {
 410                 summon_butler ();
 411         }
 412
 413         if (!_engine.freewheeling() && send_mtc) {
 414                 send_midi_time_code_in_another_thread ();
 415         }
 416
 417         return;
 418 }
 419
 420 void
 421 Session::reset_slave_state ()
 422 {
 423         average_slave_delta = 1800;
 424         delta_accumulator_cnt = 0;
 425         have_first_delta_accumulator = false;
 426         slave_state = Stopped;
 427 }
 428
 429 bool
 430 Session::transport_locked () const
 431 {
 432         Slave* sl = _slave;
 433
 434         if (!locate_pending() && ((_slave_type == None) || (sl && sl->ok() && sl->locked()))) {
 435                 return true;
 436         }
 437
 438         return false;
 439 }
 440
 441 bool
 442 Session::follow_slave (jack_nframes_t nframes, jack_nframes_t offset)
 443 {
 444         float slave_speed;
 445         jack_nframes_t slave_transport_frame;
 446         jack_nframes_t this_delta;
 447         int dir;
 448         bool starting;
 449
 450         if (!_slave->ok()) {
 451                 stop_transport ();
 452                 set_slave_source (None, 0);
 453                 goto noroll;
 454         }
 455
 456         _slave->speed_and_position (slave_speed, slave_transport_frame);
 457
 458         if (!_slave->locked()) {
 459                 goto noroll;
 460         }
 461
 462         if (slave_transport_frame > _transport_frame) {
 463                 this_delta = slave_transport_frame - _transport_frame;
 464                 dir = 1;
 465         } else {
 466                 this_delta = _transport_frame - slave_transport_frame;
 467                 dir = -1;
 468         }
 469
 470         if ((starting = _slave->starting())) {
 471                 slave_speed = 0.0f;
 472         }
 473
 474 #if 0
 475         cerr << "delta = " << (int) (dir * this_delta)
 476              << " speed = " << slave_speed
 477              << " ts = " << _transport_speed
 478              << " M@"<< slave_transport_frame << " S@" << _transport_frame
 479              << " avgdelta = " << average_slave_delta
 480              << endl;
 481 #endif
 482
 483         if (Config->get_timecode_source_is_synced()) {
 484
 485                 /* if the TC source is synced, then we assume that its
 486                    speed is binary: 0.0 or 1.0
 487                 */
 488
 489                 if (slave_speed != 0.0f) {
 490                         slave_speed = 1.0f;
 491                 }
 492
 493         } else {
 494
 495                 /* TC source is able to drift relative to us (slave)
 496                    so we need to keep track of the drift and adjust
 497                    our speed to remain locked.
 498                 */
 499
 500                 if (delta_accumulator_cnt >= delta_accumulator_size) {
 501                         have_first_delta_accumulator = true;
 502                         delta_accumulator_cnt = 0;
 503                 }
 504
 505                 if (delta_accumulator_cnt != 0 || this_delta < _current_frame_rate) {
 506                         delta_accumulator[delta_accumulator_cnt++] = dir*this_delta;
 507                 }
 508
 509                 if (have_first_delta_accumulator) {
 510                         average_slave_delta = 0;
 511                         for (int i = 0; i < delta_accumulator_size; ++i) {
 512                                 average_slave_delta += delta_accumulator[i];
 513                         }
 514                         average_slave_delta /= delta_accumulator_size;
 515                         if (average_slave_delta < 0) {
 516                                 average_dir = -1;
 517                                 average_slave_delta = -average_slave_delta;
 518                         } else {
 519                                 average_dir = 1;
 520                         }
 521                         // cerr << "avgdelta = " << average_slave_delta*average_dir << endl;
 522                 }
 523         }
 524
 525         if (slave_speed != 0.0f) {
 526
 527                 /* slave is running */
 528
 529                 switch (slave_state) {
 530                 case Stopped:
 531                         if (_slave->requires_seekahead()) {
 532                                 slave_wait_end = slave_transport_frame + _current_frame_rate;
 533                                 locate (slave_wait_end, false, false);
 534                                 slave_state = Waiting;
 535                                 starting = true;
 536
 537                         } else {
 538
 539                                 slave_state = Running;
 540
 541                                 Location* al = _locations.auto_loop_location();
 542
 543                                 if (al && auto_loop && (slave_transport_frame < al->start() || slave_transport_frame > al->end())) {
 544                                         // cancel looping
 545                                         request_auto_loop(false);
 546                                 }
 547
 548                                 if (slave_transport_frame != _transport_frame) {
 549                                         locate (slave_transport_frame, false, false);
 550                                 }
 551                         }
 552                         break;
 553
 554                 case Waiting:
 555                         break;
 556
 557                 default:
 558                         break;
 559
 560                 }
 561
 562                 if (slave_state == Waiting) {
 563
 564                         // cerr << "waiting at " << slave_transport_frame << endl;
 565
 566                         if (slave_transport_frame >= slave_wait_end) {
 567                                 // cerr << "\tstart at " << _transport_frame << endl;
 568
 569                                 slave_state = Running;
 570
 571                                 bool ok = true;
 572                                 jack_nframes_t frame_delta = slave_transport_frame - _transport_frame;
 573
 574                                 boost::shared_ptr<DiskstreamList> dsl = diskstreams.reader();
 575
 576                                 for (DiskstreamList::iterator i = dsl->begin(); i != dsl->end(); ++i) {
 577                                         if (!(*i)->can_internal_playback_seek (frame_delta)) {
 578                                                 ok = false;
 579                                                 break;
 580                                         }
 581                                 }
 582
 583                                 if (ok) {
 584                                         for (DiskstreamList::iterator i = dsl->begin(); i != dsl->end(); ++i) {
 585                                                 (*i)->internal_playback_seek (frame_delta);
 586                                         }
 587                                         _transport_frame += frame_delta;
 588
 589                                 } else {
 590                                         // cerr << "cannot micro-seek\n";
 591                                         /* XXX what? */
 592                                 }
 593
 594                                 memset (delta_accumulator, 0, sizeof (jack_nframes_t) * delta_accumulator_size);
 595                                 average_slave_delta = 0;
 596                                 this_delta = 0;
 597                         }
 598                 }
 599
 600                 if (slave_state == Running && _transport_speed == 0.0f) {
 601
 602                         // cerr << "slave starts transport\n";
 603
 604                         start_transport ();
 605                 }
 606
 607         } else {
 608
 609                 /* slave has stopped */
 610
 611                 if (_transport_speed != 0.0f) {
 612
 613                         // cerr << "slave stops transport: " << slave_speed << " frame: " << slave_transport_frame
 614                         // << " tf = " << _transport_frame
 615                         // << endl;
 616
 617                         if (_slave_type == JACK) {
 618                                 last_stop_frame = _transport_frame;
 619                         }
 620
 621                         stop_transport();
 622                 }
 623
 624                 if (slave_transport_frame != _transport_frame) {
 625                         // cerr << "slave stopped, move to " << slave_transport_frame << endl;
 626                         force_locate (slave_transport_frame, false);
 627                 }
 628
 629                 slave_state = Stopped;
 630         }
 631
 632         if (slave_state == Running && !Config->get_timecode_source_is_synced()) {
 633
 634
 635                 if (_transport_speed != 0.0f) {
 636
 637                         /*
 638                            note that average_dir is +1 or -1
 639                         */
 640
 641                         const float adjust_seconds = 1.0f;
 642                         float delta;
 643
 644                         //if (average_slave_delta == 0) {
 645                                 delta = this_delta;
 646                                 delta *= dir;
 647 //                      } else {
 648 //                              delta = average_slave_delta;
 649 //                              delta *= average_dir;
 650 //                      }
 651
 652                         float adjusted_speed = slave_speed +
 653                                 (delta / (adjust_seconds * _current_frame_rate));
 654
 655                         // cerr << "adjust using " << delta
 656                         // << " towards " << adjusted_speed
 657                         // << " ratio = " << adjusted_speed / slave_speed
 658                         // << " current = " << _transport_speed
 659                         // << " slave @ " << slave_speed
 660                         // << endl;
 661
 662                         request_transport_speed (adjusted_speed);
 663
 664 #if 1
 665                         if ((jack_nframes_t) average_slave_delta > _slave->resolution()) {
 666                                 // cerr << "not locked\n";
 667                                 goto silent_motion;
 668                         }
 669 #endif
 670                 }
 671         }
 672
 673         if (!starting && !non_realtime_work_pending()) {
 674                 /* speed is set, we're locked, and good to go */
 675                 return true;
 676         }
 677
 678   silent_motion:
 679
 680         if (slave_speed && _transport_speed) {
 681
 682                 /* something isn't right, but we should move with the master
 683                    for now.
 684                 */
 685
 686                 bool need_butler;
 687
 688                 prepare_diskstreams ();
 689                 silent_process_routes (nframes, offset);
 690                 commit_diskstreams (nframes, need_butler);
 691
 692                 if (need_butler) {
 693                         summon_butler ();
 694                 }
 695
 696                 int32_t frames_moved = (int32_t) floor (_transport_speed * nframes);
 697
 698                 if (frames_moved < 0) {
 699                         decrement_transport_position (-frames_moved);
 700                 } else {
 701                         increment_transport_position (frames_moved);
 702                 }
 703
 704                 jack_nframes_t stop_limit;
 705
 706                 if (actively_recording()) {
 707                         stop_limit = max_frames;
 708                 } else {
 709                         if (Config->get_stop_at_session_end()) {
 710                                 stop_limit = current_end_frame();
 711                         } else {
 712                                 stop_limit = max_frames;
 713                         }
 714                 }
 715
 716                 maybe_stop (stop_limit);
 717         }
 718
 719   noroll:
 720         /* don't move at all */
 721         no_roll (nframes, 0);
 722         return false;
 723 }
 724
 725 void
 726 Session::process_without_events (jack_nframes_t nframes)
 727 {
 728         bool session_needs_butler = false;
 729         jack_nframes_t stop_limit;
 730         long frames_moved;
 731
 732         {
 733                 if (post_transport_work & (PostTransportLocate|PostTransportStop)) {
 734                         no_roll (nframes, 0);
 735                         return;
 736                 }
 737
 738                 if (!_exporting && _slave) {
 739                         if (!follow_slave (nframes, 0)) {
 740                                 return;
 741                         }
 742                 }
 743
 744                 if (_transport_speed == 0) {
 745                         no_roll (nframes, 0);
 746                         return;
 747                 }
 748
 749                 if (actively_recording()) {
 750                         stop_limit = max_frames;
 751                 } else {
 752                         if (Config->get_stop_at_session_end()) {
 753                                 stop_limit = current_end_frame();
 754                         } else {
 755                                 stop_limit = max_frames;
 756                         }
 757                 }
 758
 759                 if (maybe_stop (stop_limit)) {
 760                         no_roll (nframes, 0);
 761                         return;
 762                 }
 763
 764                 click (_transport_frame, nframes, 0);
 765
 766                 prepare_diskstreams ();
 767
 768                 frames_moved = (long) floor (_transport_speed * nframes);
 769
 770                 if (process_routes (nframes, 0)) {
 771                         no_roll (nframes, 0);
 772                         return;
 773                 }
 774
 775                 commit_diskstreams (nframes, session_needs_butler);
 776
 777                 if (frames_moved < 0) {
 778                         decrement_transport_position (-frames_moved);
 779                 } else {
 780                         increment_transport_position (frames_moved);
 781                 }
 782
 783                 maybe_stop (stop_limit);
 784                 check_declick_out ();
 785
 786         } /* implicit release of route lock */
 787
 788         if (session_needs_butler) {
 789                 summon_butler ();
 790         }
 791
 792         if (!_engine.freewheeling() && send_mtc) {
 793                 send_midi_time_code_in_another_thread ();
 794         }
 795
 796         return;
 797 }
 798
 799 void
 800 Session::process_audition (jack_nframes_t nframes)
 801 {
 802         Event* ev;
 803         boost::shared_ptr<RouteList> r = routes.reader ();
 804
 805         for (RouteList::iterator i = r->begin(); i != r->end(); ++i) {
 806                 if (!(*i)->hidden()) {
 807                         (*i)->silence (nframes, 0);
 808                 }
 809         }
 810
 811         /* run the auditioner, and if it says we need butler service, ask for it */
 812
 813         if (auditioner->play_audition (nframes) > 0) {
 814                 summon_butler ();
 815         }
 816
 817         /* handle pending events */
 818
 819         while (pending_events.read (&ev, 1) == 1) {
 820                 merge_event (ev);
 821         }
 822
 823         /* if we are not in the middle of a state change,
 824            and there are immediate events queued up,
 825            process them.
 826         */
 827
 828         while (!non_realtime_work_pending() && !immediate_events.empty()) {
 829                 Event *ev = immediate_events.front ();
 830                 immediate_events.pop_front ();
 831                 process_event (ev);
 832         }
 833
 834         if (!auditioner->active()) {
 835                 process_function = &Session::process_with_events;
 836         }
 837 }
 838